org.jgrapht.alg.shortestpath

Class BidirectionalDijkstraShortestPath<V,E>

java.lang.Object

org.jgrapht.alg.shortestpath.BaseBidirectionalShortestPathAlgorithm<V,E>

org.jgrapht.alg.shortestpath.BidirectionalDijkstraShortestPath<V,E>

Type Parameters:

V - the graph vertex type

E - the graph edge type

All Implemented Interfaces:

ShortestPathAlgorithm<V,E>

public final class BidirectionalDijkstraShortestPath<V,E>
extends BaseBidirectionalShortestPathAlgorithm<V,E>

A bidirectional version of Dijkstra's algorithm.

See the Wikipedia article for details and references about bidirectional search. This technique does not change the worst-case behavior of the algorithm but reduces, in some cases, the number of visited vertices in practice. This implementation alternatively constructs forward and reverse paths from the source and target vertices respectively.

This iterator can use a custom heap implementation, which can specified during the construction time. Pairing heap is used by default

Author:

Dimitrios Michail

See Also:

DijkstraShortestPath

Nested Class Summary

Nested classes/interfaces inherited from interface org.jgrapht.alg.interfaces.ShortestPathAlgorithm

ShortestPathAlgorithm.SingleSourcePaths<V,E>

Field Summary

Fields

Modifier and Type	Field and Description
protected Graph<V,E>	graph The underlying graph.
protected static String	GRAPH_CONTAINS_A_NEGATIVE_WEIGHT_CYCLE Error message for reporting the existence of a negative-weight cycle.
protected static String	GRAPH_MUST_CONTAIN_THE_SINK_VERTEX Error message for reporting that a sink vertex is missing.
protected static String	GRAPH_MUST_CONTAIN_THE_SOURCE_VERTEX Error message for reporting that a source vertex is missing.

Constructor Summary

Constructors

Constructor and Description
BidirectionalDijkstraShortestPath(Graph<V,E> graph) Constructs a new instance for a specified graph.
BidirectionalDijkstraShortestPath(Graph<V,E> graph, double radius) Constructs a new instance for a specified graph.
BidirectionalDijkstraShortestPath(Graph<V,E> graph, double radius, Supplier<org.jheaps.AddressableHeap<Double,Pair<V,E>>> heapSupplier) Constructs a new instance for a specified graph.
BidirectionalDijkstraShortestPath(Graph<V,E> graph, Supplier<org.jheaps.AddressableHeap<Double,Pair<V,E>>> heapSupplier) Constructs a new instance for a specified graph.

Method Summary

Modifier and Type	Method and Description
protected GraphPath<V,E>	createEmptyPath(V source, V sink) Create an empty path.
static <V,E> GraphPath<V,E>	findPathBetween(Graph<V,E> graph, V source, V sink) Find a path between two vertices.
GraphPath<V,E>	getPath(V source, V sink) Get a shortest path from a source vertex to a sink vertex.
ShortestPathAlgorithm.SingleSourcePaths<V,E>	getPaths(V source) Compute all shortest paths starting from a single source vertex.
double	getPathWeight(V source, V sink) Get the weight of the shortest path from a source vertex to a sink vertex.

Methods inherited from class org.jgrapht.alg.shortestpath.BaseBidirectionalShortestPathAlgorithm

createPath

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

GRAPH_CONTAINS_A_NEGATIVE_WEIGHT_CYCLE

protected static final String GRAPH_CONTAINS_A_NEGATIVE_WEIGHT_CYCLE

Error message for reporting the existence of a negative-weight cycle.

See Also:

Constant Field Values

GRAPH_MUST_CONTAIN_THE_SOURCE_VERTEX

protected static final String GRAPH_MUST_CONTAIN_THE_SOURCE_VERTEX

Error message for reporting that a source vertex is missing.

See Also:

Constant Field Values

GRAPH_MUST_CONTAIN_THE_SINK_VERTEX

protected static final String GRAPH_MUST_CONTAIN_THE_SINK_VERTEX

Error message for reporting that a sink vertex is missing.

See Also:

Constant Field Values

graph

protected final Graph<V,E> graph

The underlying graph.

Constructor Detail

BidirectionalDijkstraShortestPath

public BidirectionalDijkstraShortestPath(Graph<V,E> graph)

Constructs a new instance for a specified graph.

Parameters:

graph - the input graph

BidirectionalDijkstraShortestPath

public BidirectionalDijkstraShortestPath(Graph<V,E> graph,
                                         Supplier<org.jheaps.AddressableHeap<Double,Pair<V,E>>> heapSupplier)

Constructs a new instance for a specified graph. The constructed algorithm will use the heap supplied by the heapSupplier.

Parameters:

graph - the input graph

heapSupplier - supplier of the preferable heap implementation

BidirectionalDijkstraShortestPath

public BidirectionalDijkstraShortestPath(Graph<V,E> graph,
                                         double radius)

Constructs a new instance for a specified graph.

Parameters:

graph - the input graph

radius - limit on path length, or Double.POSITIVE_INFINITY for unbounded search

BidirectionalDijkstraShortestPath

public BidirectionalDijkstraShortestPath(Graph<V,E> graph,
                                         double radius,
                                         Supplier<org.jheaps.AddressableHeap<Double,Pair<V,E>>> heapSupplier)

Constructs a new instance for a specified graph. The constructed algorithm will use the heap supplied by the heapSupplier.

Parameters:

graph - the input graph

radius - limit on path length, or Double.POSITIVE_INFINITY for unbounded search

heapSupplier - supplier of the preferable heap implementation

Method Detail

findPathBetween

public static <V,E> GraphPath<V,E> findPathBetween(Graph<V,E> graph,
                                                   V source,
                                                   V sink)

Find a path between two vertices. For a more advanced search (e.g. limited by radius), use the constructor instead.

Type Parameters:

V - the graph vertex type

E - the graph edge type

Parameters:

graph - the graph to be searched

source - the vertex at which the path should start

sink - the vertex at which the path should end

Returns:

a shortest path, or null if no path exists

getPath

public GraphPath<V,E> getPath(V source,
                              V sink)

Description copied from interface: ShortestPathAlgorithm

Get a shortest path from a source vertex to a sink vertex.

Parameters:

source - the source vertex

sink - the target vertex

Returns:

a shortest path or null if no path exists

getPaths

public ShortestPathAlgorithm.SingleSourcePaths<V,E> getPaths(V source)

Compute all shortest paths starting from a single source vertex.

Specified by:

getPaths in interface ShortestPathAlgorithm<V,E>

Parameters:

source - the source vertex

Returns:

the shortest paths

getPathWeight

public double getPathWeight(V source,
                            V sink)

Get the weight of the shortest path from a source vertex to a sink vertex. Returns Double.POSITIVE_INFINITY if no path exists.

Specified by:

getPathWeight in interface ShortestPathAlgorithm<V,E>

Parameters:

source - the source vertex

sink - the sink vertex

Returns:

the weight of the shortest path from a source vertex to a sink vertex, or Double.POSITIVE_INFINITY if no path exists

createEmptyPath

protected final GraphPath<V,E> createEmptyPath(V source,
                                               V sink)

Create an empty path. Returns null if the source vertex is different than the target vertex.

Parameters:

source - the source vertex

sink - the sink vertex

Returns:

an empty path or null null if the source vertex is different than the target vertex